When running as a unified agent (pulse-agent with --enable-docker), the
Docker module was using a different fallback chain for agent ID than the
host module. In unified mode with empty machineID, the Docker module fell
back to daemonID while the host module fell back to hostname. This caused
the server to reject Docker reports with 'token already in use by agent'
errors because the same API token was bound to different agent IDs.
The fix ensures that in unified mode, the Docker module uses the exact
same fallback chain as the host module: machineID -> hostname. The daemonID
fallback is only used in standalone mode for backward compatibility.
Fixes#985, #986
rcourtman
d804471889